| 摘要 |
PURPOSE:To improve the dispersibility of magnetic particles and to obtain a magnetic recording medium of a radiation curing type having an excellent magnetic characteristic, surface smoothness and durability by using a specific binder in combination with pretreated magnetic powder. CONSTITUTION:Magnetic powder is subjected to a surface treatment by a silane coupling agent having a vinyl group. The treatment process is executed by dissolving the silane coupling agent into a suitable solvent, for example, a water/ alcohol mixture, immersing the magnetic powder therein and evaporating the solvent as it is or removing the solvent by a means such as spray drying or the like. gamma-Fe2O3, Fe3O4 and iron oxide in the intermediate oxidized state of gamma- Fe2O3 and Fe3O4, Co-contg. gamma-Fe2O3 alloy, etc. are used as the magnetic powder for raw material. A vinyl monomer having a hydroxy group or a monomer mixture composed of said monomer and the other vinyl monomer is graft-polymerized to the surface-treated magnetic powder obtd. in the above-mentioned way. The amt. of the vinyl monomer contg. the hydroxy group or the vinyl monomer mixture to be used is adequately about 10-100wt% by the weight of the surface-treated magnetic powder.
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